/*
** Authored by Timothy Gerard Endres
** <mailto:time@gjt.org>  <http://www.trustice.com>
** 
** This work has been placed into the public domain.
** You may use this work in any way and for any purpose you wish.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE. 
** 
*/

package be.djdb.externstuff.tuned;
import java.io.*;
import javax.activation.*;

/**
 * The TarInputStream reads a UNIX tar archive as an InputStream.
 * methods are provided to position at each successive entry in
 * the archive, and the read each entry as a normal input stream
 * using read().
 * Kerry Menzel <kmenzel@cfl.rr.com> Contributed the code to support
 * file sizes greater than 2GB (longs versus ints).
 * @version $Revision: 1.9 $
 * @author Timothy Gerard Endres, <time@gjt.org>
 * @see TarBuffer
 * @see TarHeader
 * @see TarEntry
 */
public class TarInputStream extends		FilterInputStream{
	private static final boolean DEBUG = true;
	protected boolean			hasHitEOF;
	protected long				entrySize;
	protected long				entryOffset;
	protected byte[]			oneBuf;
	protected byte[]			readBuf;
	protected TarBuffer			buffer;
	protected TarEntry			currEntry;
	protected EntryFactory		eFactory;
	public	TarInputStream(InputStream is){
		this( is, TarBuffer.DEFAULT_BLKSIZE, TarBuffer.DEFAULT_RCDSIZE );
	}
	public	TarInputStream(InputStream is, int blockSize){
		this( is, blockSize, TarBuffer.DEFAULT_RCDSIZE );
	}
	public	TarInputStream(InputStream is, int blockSize, int recordSize){
		super(is);
		this.buffer = new TarBuffer(is, blockSize, recordSize );
		this.readBuf = null;
		this.oneBuf = new byte[1];
		this.hasHitEOF = false;
		this.eFactory = null;
	}
	/**
	 * Sets the debugging flag.
	 * @param debugF True to turn on debugging.
	 */
	public void	setEntryFactory( EntryFactory factory ){
		this.eFactory = factory;
	}

	/**
	 * Closes this stream. Calls the TarBuffer's close() method.
	 */
	public void	close()	throws IOException{
		this.buffer.close();
	}
	/**
	 * Get the record size being used by this stream's TarBuffer.
	 * @return The TarBuffer record size.
	 */
	public int	getRecordSize()	{
		return this.buffer.getRecordSize();
	}
	/**
	 * Get the available data that can be read from the current entry in the archive. This does not indicate how much data is left in the entire archive, only in the current entry. This value is determined from the entry's size header field
	 * and the amount of data already read from the current entry.
	 * @return The number of available bytes for the current entry.
	 */
	public int	available()	throws IOException	{
		return (int)(this.entrySize - this.entryOffset);
	}
	/**
	 * Skip bytes in the input buffer. This skips bytes in the current entry's data, not the entire archive, and will stop at the end of the current entry's data if the number to skip extends beyond that point.
	 * @param numToSkip The number of bytes to skip.
	 * @return The actual number of bytes skipped.
	 */
	public long	skip( long numToSkip )throws IOException{
		// REVIEW
		// This is horribly inefficient, but it ensures that we
		// properly skip over bytes via the TarBuffer...
		//
		byte[] skipBuf = new byte[ 8 * 1024 ];
        long num = numToSkip;
		for( ; num > 0 ; ){
			int numRead = this.read( skipBuf, 0,( num > skipBuf.length ? skipBuf.length : (int) num ) );
				if ( numRead == -1 )
					break;
			num -= numRead;
		}
	return ( numToSkip - num );
	}
	/**
	 * Since we do not support marking just yet, we return false.
	 * @return False.
	 */
	public boolean	markSupported()		{
		return false;
	}
	/**
	 * Since we do not support marking just yet, we do nothing.
	 * @param markLimit The limit to mark.
	 */
	public void	mark( int markLimit ){
	}
	/**
	 * Since we do not support marking just yet, we do nothing.
	 */
	public void	reset()	{
	}
	/**
	 * Get the number of bytes into the current TarEntry. This method returns the number of bytes that have been read from the current TarEntry's data.
	 * @returns The current entry offset.
	 */
	public long	getEntryPosition()	{
		return this.entryOffset;
	}
	/**
	 * Get the number of bytes into the stream we are currently at. This method accounts for the blocking stream that tar uses,
	 * so it represents the actual position in input stream, as opposed to the place where the tar archive parsing is.
	 * @returns The current file pointer.
	 */
	public long	getStreamPosition()	{
		return ( buffer.getBlockSize() * buffer.getCurrentBlockNum() )	+ buffer.getCurrentRecordNum();
	}
	/**
	 * Get the next entry in this tar archive. This will skip over any remaining data in the current entry, if there is one, and place the input stream at the header of the next entry, and read the header and instantiate a new
	 * TarEntry from the header bytes and return that entry. If there are no more entries in the archive, null will be returned to indicate that the end of the archive has been reached.
	 * @return The next TarEntry in the archive, or null.
	 */
	public TarEntry	getNextEntry()	throws IOException	{
		if ( this.hasHitEOF )
			return null;
		if ( this.currEntry != null ){
			long numToSkip = (this.entrySize - this.entryOffset);
			if (DEBUG)System.err.println( "TarInputStream: SKIP currENTRY '"+ this.currEntry.getName() + "' SZ "+ this.entrySize + " OFF " + this.entryOffset+ "  skipping " + numToSkip + " bytes" );
			if ( numToSkip > 0 ){
				this.skip( numToSkip );
			}
			this.readBuf = null;
		}
		byte[] headerBuf = this.buffer.readRecord();
		if(headerBuf == null){
			if(DEBUG){System.err.println( "READ NULL RECORD" );}
			this.hasHitEOF = true;
		}else if ( this.buffer.isEOFRecord( headerBuf ) ){
			if (DEBUG){System.err.println( "READ EOF RECORD" );}
			this.hasHitEOF = true;
		}
		if ( this.hasHitEOF ){
			this.currEntry = null;
		}else{
			try {
				if ( this.eFactory == null ){
					this.currEntry = new TarEntry( headerBuf );
				}else{
					this.currEntry = this.eFactory.createEntry( headerBuf );
				}
				if (DEBUG)System.err.println( "TarInputStream: SET CURRENTRY '"+ this.currEntry.getName()+ "' size = " + this.currEntry.getSize());
				this.entryOffset = 0;
				this.entrySize = this.currEntry.getSize();
			}catch ( InvalidHeaderException ex ){
				this.entrySize = 0;
				this.entryOffset = 0;
				this.currEntry = null;
				throw new InvalidHeaderException( "bad header in block "+ this.buffer.getCurrentBlockNum()+ " record "+ this.buffer.getCurrentRecordNum()	+ ", " + ex.getMessage() );
				}
			}
		return this.currEntry;
		}
	/**
	 * Reads a byte from the current tar archive entry. This method simply calls read( byte[], int, int ).
	 * @return The byte read, or -1 at EOF.
	 */
	public int read()throws IOException	{
		int num = this.read( this.oneBuf, 0, 1 );
		if ( num == -1 )
			return num;
		else
			return (int) this.oneBuf[0];
		}
	/**
	 * Reads bytes from the current tar archive entry. This method simply calls read( byte[], int, int ).
	 * @param buf The buffer into which to place bytes read.
	 * @return The number of bytes read, or -1 at EOF.
	 */
	public int	read( byte[] buf )throws IOException{
		return this.read( buf, 0, buf.length );
	}
	/**
	 * Reads bytes from the current tar archive entry.
	 * This method is aware of the boundaries of the current entry in the archive and will deal with them as if they were this stream's start and EOF.
	 * @param buf The buffer into which to place bytes read.
	 * @param offset The offset at which to place bytes read.
	 * @param numToRead The number of bytes to read.
	 * @return The number of bytes read, or -1 at EOF.
	 */
	public int	read( byte[] buf, int offset, int numToRead )throws IOException	{
		int totalRead = 0;
		if ( this.entryOffset >= this.entrySize )
			return -1;
		if ( (numToRead + this.entryOffset) > this.entrySize ){
			numToRead = (int) (this.entrySize - this.entryOffset);
		}
		if ( this.readBuf != null )	{
			int sz = ( numToRead > this.readBuf.length )? this.readBuf.length : numToRead;
			System.arraycopy( this.readBuf, 0, buf, offset, sz );
			if ( sz >= this.readBuf.length ){
				this.readBuf = null;
			}else{
				int newLen = this.readBuf.length - sz;
				byte[] newBuf = new byte[ newLen ];
				System.arraycopy( this.readBuf, sz, newBuf, 0, newLen );
				this.readBuf = newBuf;
			}
			totalRead += sz;
			numToRead -= sz;
			offset += sz;
		}
		for ( ; numToRead > 0 ; ){
			byte[] rec = this.buffer.readRecord();
			if ( rec == null ){
				// Unexpected EOF!
				throw new IOException( "unexpected EOF with " + numToRead + " bytes unread" );
			}
			int sz = numToRead;
			int recLen = rec.length;
			if ( recLen > sz ){
				System.arraycopy( rec, 0, buf, offset, sz );
				this.readBuf = new byte[ recLen - sz ];
				System.arraycopy( rec, sz, this.readBuf, 0, recLen - sz );
			}else{
				sz = recLen;
				System.arraycopy( rec, 0, buf, offset, recLen );
			}
			totalRead += sz;
			numToRead -= sz;
			offset += sz;
		}
		this.entryOffset += totalRead;
		return totalRead;
		}
	/**
	 * Copies the contents of the current tar archive entry directly into an output stream.
	 * @param out The OutputStream into which to write the entry's data.
	 */
	public void	copyEntryContents( OutputStream out )throws IOException	{
		byte[] buf = new byte[ 32 * 1024 ];
		for ( ; ; ){
			int numRead = this.read( buf, 0, buf.length );
			if ( numRead == -1 )
				break;
			out.write( buf, 0, numRead );
			}
		}
	/**
	 * This interface is provided, with the method setEntryFactory(), to allow the programmer to have their own TarEntry subclass instantiated for the
	 * entries return from getNextEntry().
	 */
	public	interface	EntryFactory{
		public TarEntry	createEntry( String name );
		public TarEntry	createEntry( File path )throws InvalidHeaderException;
		public TarEntry	createEntry( byte[] headerBuf )throws InvalidHeaderException;
	}
	public	class EntryAdapter	implements	EntryFactory{
		public TarEntry	createEntry( String name ){
			return new TarEntry( name );
		}
		public TarEntry	createEntry( File path )throws InvalidHeaderException	{
			return new TarEntry( path );
		}
		public TarEntry	createEntry( byte[] headerBuf )	throws InvalidHeaderException{
			return new TarEntry( headerBuf );
		}
	}
}// no crimalcode Tuned by Lieven


